Control device of gear transmission-equipped vehicle and method of controlling gear transmission-equipped vehicle

ABSTRACT

A control device of a gear transmission-equipped vehicle includes a power controller that starts power reduction control when it is determined that a start condition is satisfied, the power reduction control being control of reducing power transmitted from a driving source to a gear transmission. The start condition includes: a condition that a detection value of a gear position sensor that detects a current gear position of the gear transmission falls within a transition region between engagement regions corresponding to respective gear positions; and a condition that a speed difference obtained by subtracting a rotational speed of an output shaft of the gear transmission from a rotational speed of an input shaft of the gear transmission is a threshold or more.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of U.S. patent application Ser.No. 17/402,143, filed Aug. 13, 2021, and entitled CONTROL DEVICE OF GEARTRANSMISSION-EQUIPPED VEHICLE AND METHOD OF CONTROLLING GEARTRANSMISSION-EQUIPPED VEHICLE, which in turn claims priority to JapanesePatent Application No. 2020-171785, filed on Oct. 12, 2020, the entiredisclosures of which are hereby incorporated herein by reference for allpurposes.

BACKGROUND OF THE INVENTION Technical Field

The present disclosure relates to a control device of a geartransmission-equipped vehicle.

Description of the Related Art

An engine vehicle including a gear transmission is known (see JapaneseLaid-Open Patent Application Publication No. 2019-85894, for example).In a gear transmission, when a shift drum rotates, and a shift forkslides a gear selector, the gear selector is engaged with a gear, and aspeed change path of a desired change gear ratio becomes a powertransmitting state.

However, when the engagement of the gear selector with the gear isincomplete at the time of the completion of a speed change operation,the gear selector may be unintentionally disengaged from the gearalthough next speed change manipulation is not being performed (geardisengagement). When the gear selector is disengaged from the gear, loadapplied from a road surface to a driving wheel is not transmitted to anengine, and a rotational speed of the engine increases sharply.Therefore, when the gear selector is reengaged with the gear after beingdisengaged from the gear, shock is generated due to a speed differencebetween the gear and the gear selector.

SUMMARY OF THE INVENTION

A control device of a gear transmission-equipped vehicle according toone aspect of the present disclosure is a control device of a geartransmission-equipped vehicle, the gear transmission-equipped vehicleincluding a driving source and a gear transmission that changes arotational speed of power output from the driving source, the controldevice including: a condition determiner that determines whether or nota predetermined start condition is satisfied; and a power controllerthat starts power reduction control when the condition determinerdetermines that the start condition is satisfied, the power reductioncontrol being control of reducing the power transmitted from the drivingsource to the gear transmission. The start condition includes: acondition that a detection value of a gear position sensor that detectsa current gear position of the gear transmission falls within atransition region between engagement regions corresponding to respectivegear positions; and a condition that a speed difference obtained bysubtracting a rotational speed of an output shaft of the geartransmission from a rotational speed of an input shaft of the geartransmission is a threshold or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left side view of a motorcycle.

FIG. 2 is a sectional view taken along a plane passing throughrespective shafts of a gear transmission of the motorcycle shown in FIG.1 .

FIG. 3 is a development view of a shift drum shown in FIG. 2 .

FIG. 4 is a block diagram showing a control device and the likeaccording to Embodiment 1.

FIG. 5 is a graph showing detection values of a gear position sensorshown in FIG. 4 .

FIG. 6 is a flow chart for explaining control of the control deviceshown in FIG. 4 .

FIG. 7 is a block diagram showing the control device and the likeaccording to Embodiment 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments will be described with reference to thedrawings.

FIG. 1 is a left side view of a motorcycle 1. As shown in FIG. 1 , themotorcycle 1 includes a vehicle body frame 2 and front and rear wheels 3and 4 supported by the vehicle body frame 2. The front wheel 3 is adriven wheel, and the rear wheel 4 is a driving wheel. The motorcycle 1is one example of a gear transmission-equipped vehicle. The geartransmission-equipped vehicle is not limited to a motorcycle and may bea different type of vehicle (for example, a straddle vehicle, such as athree-wheeled motorcycle).

The vehicle body frame 2 includes a head pipe 2 a, a main frame 2 b, anda pivot frame 2 c. The main frame 2 b extends rearward from the headpipe 2 a. The pivot frame 2 c is connected to a rear portion of the mainframe 2 b. The head pipe 2 a supports a steering shaft such that thesteering shaft is rotatable. The steering shaft is connected to a barhandle 5 held by a rider R. The front wheel 3 is steered to a leftdirection or a right direction by the rotation of the steering shaft.

A fuel tank 6 is arranged behind the handle 5 and at an upper side ofthe main frame 2 b. A seat 7 on which the rider R is seated is arrangedbehind the fuel tank 6. Steps 8 on which the rider R places his/her feetare arranged under and at left and right sides of the seat 7. A shiftoperating body 9 (shift lever) is arranged close to one of the steps 8and is manipulated by the foot placed on the step 8. A front end portionof a swing arm 10 is supported by the pivot frame 2 c, and the rearwheel 4 is supported by a rear end portion of the swing arm 10.

An engine E (driving source) supported by the main frame 2 b and thepivot frame 2 c is arranged between the front wheel 3 and the rear wheel4. The engine E is an internal combustion engine as a driving sourcethat generates traveling power. Instead of the engine E, an electricmotor may be used as the driving source. Or, both the engine and theelectric motor may be used as the driving sources.

A gear transmission 11 is connected to a crank shaft Ea of the engine Esuch that the crank shaft Ea of the engine E can transmit the power tothe gear transmission 11. Driving force output from the geartransmission 11 is transmitted to the rear wheel 4 through a powertransmitting structure 13 (for example, a chain or a belt). The crankshaft Ea of the engine E is housed in a crank case 14 supported by thevehicle body frame 2. The crank case 14 also houses the geartransmission 11, i.e., also serves as a transmission case. Themotorcycle 1 is equipped with a control device 12 (ECU) that controlsthe engine E.

FIG. 2 is a sectional view taken along a plane passing throughrespective shafts of the gear transmission 11 of the motorcycle 1 showsin FIG. 1 . As shown in FIG. 2 , the gear transmission 11 includes aninput shaft 15, an output shaft 16, and transmission gear pairs 17 thathave different reduction ratios from each other. The gear transmission11 can selectively set a desired one of the transmission gear pairs 17to a power transmitting state to change the rotational speed of thepower transmitted from the input shaft 15 to the output shaft 16. Thepower is transmitted from the crank shaft Ea of the engine E to theinput shaft 15 of the gear transmission 11. The power transmittingstructure 13 (see FIG. 1 ) that transmits the power of the output shaft16 to the rear wheel 4 is engaged with the output shaft 16.

A main clutch C is interposed between the engine E and the input shaft15. To be specific, a power transmitting path from the engine E to thegear transmission 11 can be cut by the main clutch C. The main clutch Cis a friction clutch (for example, a multiple disc clutch) and canrealize a half-engaged state. To be specific, the main clutch C cancontinuously change a power transmitting ratio between a disengagedstate and a completely engaged state.

The gear transmission 11 is a dog gear transmission. The geartransmission 11 selects one of the transmission gear pairs 17 bymechanical connection with the manipulation of the rider to switch thepower transmitting path, i.e., perform speed change. The geartransmission 11 includes gears 17 a, dog gears 17 b to 17 d (engagingmembers), shift forks 19 to 21, and a shift drum 22. Each of the gears17 a is fitted to the input shaft 15 or the output shaft 16 so as to berotatable relative to the input shaft 15 or the output shaft 16. Each ofthe dog gears 17 b to 17 d is fitted to the input shaft 15 or the outputshaft 16 so as to rotate together with the input shaft 15 or the outputshaft 16.

The gear 17 a includes a dog hole H on a side surface thereof. Each ofthe dog gears 17 b to 17 d includes a dog D projecting from a sidesurface thereof toward the adjacent gear 17 a. The dog gear 17 b isdisposed at the input shaft 15 so as to be slidable relative to theinput shaft 15. The dog gears 17 c and 17 d are disposed at the outputshaft 16 so as to be slidable relative to the output shaft 16. However,the gears 17 a may include the dogs D, and the dog gears 17 b to 17 dmay include the dog holes H.

The shift forks 19 to 21 are supported by spindles 18 so as to beslidable relative to the spindles 18. The spindles 18 are disposed inparallel with the input shaft 15 and the output shaft 16. A tip portionof the shift fork 19 is connected to the dog gear 17 b of the inputshaft 15. Tip portions of the shift forks 20 and 21 are respectivelyconnected to the dog gears 17 c and 17 d of the output shaft 16. Baseportions of the shift forks 19 to 21 are fitted to respective guidegrooves G on an outer peripheral surface of the shift drum 22.

The shift drum 22 rotates by mechanical connection with shiftmanipulation of the shift operating body 9 (see FIG. 1 ) manipulated bythe rider R. The shift drum 22 may be driven by an actuator to rotate.The shift forks 19 to 21 guided by the guide grooves G of the rotatingshift drum 22 slide the corresponding dog gears 17 b to 17 d along theinput shaft 15 or the output shaft 16.

With this, the dog D of any of the dog gears 17 b to 17 d is engagedwith the dog hole H of any of the gears 17 a. As a result, thetransmission gear pair 17 having the reduction ratio desired by therider R among the transmission gear pairs 17 becomes the powertransmitting state. Thus, the power transmitting path of a desired gearstage is selected. To be specific, each of the dog gears 17 b to 17 dserves as a gear selector that is selectively engaged with a desired oneof the gears 17 a to realize the desired gear stage. In the presentembodiment, the gear selector that is slid by the shift fork is the doggear. However, instead of the dog gear, a dog that is not a gear may beused as the gear selector.

A gear position sensor 23 is engaged with the shift drum 22. The gearposition sensor 23 outputs a detection value (voltage) corresponding toa phase angle (rotation angle) of the shift drum 22. Since the phaseangle of the shift drum 22 corresponds to a current gear stage of thegear transmission 11, the detection value of the gear position sensor 23indicates the current gear stage of the gear transmission 11.

FIG. 3 is a development view of the shift drum 22 shown in FIG. 2 . Asshown in FIG. 3 , each of the guide grooves G of the shift drum 22includes engagement regions A₁ to A₆ corresponding to respective gearstages (for example, first to sixth speeds). When the shift forks 19 to21 (see FIG. 2 ) are located in any of the engagement regions A₁ and A₆of the guide grooves G of the shift drum 22, the dog D of any of the doggears 17 b to 17 d (see FIG. 2 ) is engaged with the dog hole H of anyof the gears 17 a (see FIG. 2 ). Each of neutral regions A_(N) isbetween the engagement region A₁ corresponding to the first speed andthe engagement region A₂ corresponding to the second speed. When theshift forks 19 to 21 are located in the corresponding neutral regionsA_(N), the dogs D of the dog gears 17 b to 17 d are not engaged with thedog holes H of the gears 17 a.

Each of the guide grooves G of the shift drum 22 includes transitionregions B₁ to B₅ each located between adjacent two of the engagementregions A₁ and A₆. When the shift forks 19 to 21 are located in any ofthe transition regions B₁ to B₅ of the guide grooves G of the shift drum22, the dogs D of the dog gears 17 b to 17 d are not engaged with thedog holes H of the gears 17 a. To be specific, when the shift forks 19to 21 are located in any of the transition regions B₁ to B₅ of the guidegrooves G of the shift drum 22, the power transmitting path between theinput shaft 15 and the output shaft 16 is cut, and load transmitted froma road surface through the rear wheel 4 to the gear transmission 11 isnot transmitted to the engine E. Each of the transition regions B₁ isbetween the neutral region A_(N) and the engagement region A₁, and eachof the transition regions B_(N) is between the neutral region A_(N) andthe engagement region A₂. When each of the shift forks 19 to 21 islocated in the corresponding continuous regions B₁, A_(N), and B_(N),the dogs D of the dog gears 17 b to 17 d are not engaged with the dogholes H of the gears 17 a.

In a speed change operation, each of the shift forks 19 to 21 moves fromthe current engagement region (one of the engagement regions A₁ and A₆)through the adjacent transition region (one of the transition regions B₁to B₅) to the next engagement region (another one of the engagementregions A₁ and A₆). When each of the shift forks 19 to 21 moves from thecurrent engagement region to the transition region, the dog D isdisengaged from the dog hole H. When each of the shift forks 19 to 21moves from the transition region to the next engagement region, the dogD is engaged with the dog hole H. Thus, the speed change operation iscompleted.

When the engagement of the dog D of the dog gear 17 b, 17 c, or 17 dwith the dog hole H of the gear 17 a is incomplete after the completionof the speed change operation, the dog D may be unintentionallydisengaged from the dog hole H although the next speed change operationis not being performed. When such unintentional gear disengagement (gearslipout; jump out of gear) occurs, each of the shift forks 19 to 21moves from the engagement region (one of the engagement regions A₁ andA₆) to the transition region (one of the transition regions B₁ to B₅) inaccordance with the movement of the dog gear (one of the dog gears 17 bto 17 d). When such gear disengagement occurs, the load applied from theroad surface to the rear wheel 4 is not transmitted to the engine E, andthe rotational speed of the engine E increases sharply. A state wherethe shift forks 19 to 21 are located in the neutral regions A_(N)corresponds to a state where the dogs D are intentionally disengagedfrom the dog holes H. Therefore, this is not the gear disengagement inthe present embodiment.

Embodiment 1

FIG. 4 is a block diagram showing the control device 12 and the likeaccording to Embodiment 1. As shown in FIG. 4 , the control device 12includes a condition determiner 31 and an engine controller 32 (powercontroller) in terms of functions. The control device 12 includes aprocessor, a memory, an I/O interface, and the like in terms ofhardware. The memory includes a storage (a hard disk, a flash memory,etc.) and a main memory (RAM). Each of the condition determiner 31 andthe engine controller 32 is realized in such a manner that the processorutilizes the main memory to perform calculation processing based on aprogram stored in the storage.

The gear position sensor 23, an engine rotational frequency sensor 24, arear wheel vehicle speed sensor 25, a throttle opening degree sensor 26,a clutch switch 27, and the like are electrically connected to an inputside of the control device 12. A throttle device 41, an ignition device42, a fuel supply device 43, and the like are electrically connected toan output side of the control device 12.

The gear position sensor 23 outputs the detection value (voltage)corresponding to the phase angle of the shift drum 22 to indicate thecurrent gear stage of the gear transmission 11. The engine rotationalfrequency sensor 24 detects the rotational speed of the engine E. Therear wheel vehicle speed sensor 25 detects the rotational speed of therear wheel 4. The throttle opening degree sensor 26 detects a throttleopening degree of a throttle valve of the throttle device 41. The clutchswitch 27 detects whether the main clutch C is in an engaged state or adisengaged state.

The throttle device 41 adjusts the amount of intake air supplied to theengine E. The ignition device 42 ignites a fuel-air mixture in acombustion chamber of the engine E and can adjust an ignition timing.The fuel supply device 43 supplies fuel to the engine E and can adjustthe amount of fuel supplied. To be specific, the engine E is controlledby controlling at least one of the throttle device 41, the ignitiondevice 42, and the fuel supply device 43.

The condition determiner 31 determines a condition of executing powerreduction control of suppressing a sharp increase in engine rotationalspeed at the time of the occurrence of the gear disengagement.Specifically, the condition determiner 31 determines whether or not astart condition of starting the power reduction control is satisfiedduring the operation of the engine E. The condition determiner 31determines whether or not a termination condition of terminating thepower reduction control is satisfied during the execution of the powerreduction control.

When it is determined that the start condition is satisfied, the enginecontroller 32 starts the power reduction control of reducing the powertransmitted from the engine E to the gear transmission 11. The powerreduction control in the present embodiment is control of reducing theoutput of the engine E. Specifically, the power reduction controlincludes: controlling the throttle device 41 to reduce the amount ofintake air; controlling the ignition device 42 to retard the ignitiontiming or not to perform ignition; and/or controlling the fuel supplydevice 43 to reduce the amount of fuel supplied.

FIG. 5 is a graph showing the detection values of the gear positionsensor 23 shown in FIG. 4 . As shown in FIG. 5 , the detection values ofthe gear position sensor 23 indicate the positions of the shift forks 19to 21 in the guide grooves G of the shift drum 22. In FIG. 5 , adetection value range V_(A1) corresponds to the engagement region A₁, adetection value range V_(B1) corresponds to the transition region B₁, adetection value range V_(AN) corresponds to the neutral region A_(N), adetection value range V_(BN) corresponds to the transition region B_(N),a detection value range V_(A2) corresponds to the engagement region A₂,a detection value range V_(B2) corresponds to the transition region B₂,and a detection value range V_(A3) corresponds to the engagement regionA₃. To be specific, the condition determiner 31 (see FIG. 4 ) can findthe region in which the shift forks 19 to 21 are located among theengagement regions A₁ and A₆, the transition regions B₁ to B₅ and B_(N),and the neutral region A_(N) by confirming the detection value regionwithin which the detection value of the gear position sensor 23 falls.

FIG. 6 is a flow chart for explaining control of the control device 12shown in FIG. 4 . The following will be descried based on the flow chartof FIG. 6 with suitable reference to FIGS. 2 to 4 . The conditiondeterminer 31 of the control device 12 determines whether or not thestart condition of starting the power reduction control is satisfiedduring the operation of the engine E. In other words, the conditiondeterminer 31 determines whether or not the gear disengagement is beingcaused. The start condition includes conditions of Steps S1 to S3.Specifically, the condition determiner 31 first determines whether ornot a control precondition is satisfied (Step S1).

When the control precondition is not satisfied (No in Step S1), thecontrol device 12 returns to Step 51. The control precondition includesa condition that the main clutch C is in the engaged state. To bespecific, even when the engine rotational speed increases with the mainclutch C in the disengaged state, the rotational speed of the inputshaft 15 of the gear transmission 11 does not increase. Therefore, byeliminating the disengaged state of the main clutch C from the startcondition, the power reduction control is prevented from being executedunnecessarily.

The control precondition further includes a condition that the detectionvalue of the gear position sensor 23 falls within a region (non-neutralregion) other than the neutral region A_(N). To be specific, the statewhere the shift forks 19 to 21 are located at the neutral regions A_(N)(not the transition regions) corresponds to the state where the riderhas intentionally caused the gear disengagement. Therefore, byeliminating the neutral region A_(N) from the start condition, the powerreduction control is prevented from being executed unnecessarily.

The control precondition further includes a condition that the magnitudeof the power transmitted from the engine E to the gear transmission 11is a predetermined lower limit or more. More specifically, the controlprecondition includes: a condition that the engine rotational speed is apredetermined lower limit or more; and a condition that the throttleopening degree is a predetermined lower limit or more.

With this, since the power reduction control is not executed when theengine rotational speed is low, jerky feeling is prevented from beinggiven to the rider at the time of engine low rotation. Moreover, whenthe throttle opening degree is less than the lower limit, and a sharpincrease in the engine rotational speed hardly occurs, the powerreduction control is prevented from being executed unnecessarily.

The control precondition further includes a condition that the magnitudeof the power transmitted from the engine E to the gear transmission 11is a predetermined upper limit or less. More specifically, the controlprecondition includes: a condition that the engine rotational speed is apredetermined upper limit or less; and a condition that the throttleopening degree is a predetermined upper limit or less.

With this, at the time of engine high rotation in which a speeddifference δV tends to become large even in the normal speed changeoperation, the normal speed change operation is prevented from beingmistakenly determined as the gear disengagement. Moreover, at the timeof the engine high rotation in which meshing force of gears is strong,and the gear disengagement hardly occurs, the power reduction control isprevented from being executed unnecessarily. The above-describedconditions included in the control precondition do not have to beessential and may be arbitrarily selected and used.

When the control precondition is satisfied (Yes in Step S1), thecondition determiner 31 determines whether or not the detection value ofthe gear position sensor 23 falls within any of the detection valueranges V_(B1) to V_(B5) and V_(BN) corresponding to the transitionregions B₁ to B₅ and B_(N) (Step S2). When the detection value of thegear position sensor 23 does not fall within any of the detection valueranges V_(B1) to V_(B5) and V_(BN) (transition regions B₁ to B₅ andB_(N)) (No in Step S2), the control device 12 returns to Step S1. Whenthe detection value of the gear position sensor 23 falls within any ofthe detection value ranges V_(B1) to V_(B5) and V_(BN) (transitionregions B₁ to B₅ and B_(N)) (Yes in Step S2), the control device 12determines whether or not the speed difference δV is a threshold TH ormore (Step S3). The speed difference δV is a value (=V_(I)−V_(O))obtained by subtracting a rotational speed V_(O) of the output shaft 16from a rotational speed V_(I) of the input shaft 15.

The rotational speed V_(I) of the input shaft 15 is obtained bymultiplying the engine rotational speed detected by the enginerotational frequency sensor 24 by a speed ratio (reduction ratio) of thepower transmitting path from the engine E to the input shaft 15. Therotational speed V_(O) of the output shaft 16 is obtained by multiplyingthe rotational speed of the rear wheel 4 detected by the rear wheelvehicle speed sensor 25 by a speed ratio of the power transmitting pathfrom the rear wheel 4 to the output shaft 16. Each of the rotationalspeed V_(I) of the input shaft 15 and the rotational speed V_(O) of theoutput shaft 16 may be directly detected by a sensor.

The condition determiner 31 sets the threshold TH such that thethreshold TH increases as the rotational speed of the engine Edecreases. To be specific, shock generated by reengagement performedafter the occurrence of the gear disengagement is smaller in the enginelow-speed range than in the engine high-speed range. Therefore, bysetting the power reduction control such that the power reductioncontrol hardly starts in the engine low-speed range, the power reductioncontrol is prevented from being executed unnecessarily.

When the speed difference δV is not the threshold TH or more (No in StepS3), the control device 12 returns to Step S1. When the speed differenceδV is the threshold TH or more (Yes in Step S3), it is determined thatthe start condition is satisfied, and therefore, the power reductioncontrol is started (Step S4). To be specific, Steps S1 to S3 are stepsof determining whether or not the gear disengagement in which the doggears 17 b to 17 d are disengaged from the gears 17 a has occurred aftera speed change step is terminated. Step S4 is a step of reducing thepower transmitted from the engine E to the gear transmission 11.

As described above, when it is determined that the gear disengagementhas occurred, the power reduction control is executed. Therefore, thespeed difference δV between the rotational speed V_(I) of the inputshaft 15 and the rotational speed V_(O) of the output shaft 16 in thegear transmission 11 is prevented from becoming excessive. Therefore,the shock generated by the reengagement performed after the geardisengagement has unintentionally occurred is reduced.

Next, the condition determiner 31 determines whether or not thetermination condition is satisfied during the execution of the powerreduction control (Step S5). The termination condition includes acondition that an absolute value of the speed difference δV is apredetermined value or less. The predetermined value is preferably 300to 2,000 rpm, more preferably 500 to 1,500 rpm (for example, 1,000 rpm).When this condition is satisfied, the feeling of the rider is preventedfrom deteriorating even after the power reduction control is terminated.

The termination condition further includes a condition that thedetection value of the gear position sensor 23 falls within any of theengagement regions A₁ and A₆. With this, since the power reductioncontrol is terminated after the completion of the reengagement performedafter the gear disengagement has occurred, the shock generated by thereengagement performed after the occurrence of the gear disengagement issurely prevented. The above two conditions included in the terminationcondition do not have to be essential and may be arbitrarily selectedand used.

When the termination condition is not satisfied (No in Step S5), thepower reduction control is continued. When the termination condition issatisfied (Yes in Step S5), the control device 12 determines whether ornot a predetermined delay time has elapsed since the terminationcondition is satisfied (Step S6). When the delay time has not elapsed(No in Step S6), the control device 12 returns to Step S5. When thedelay time has elapsed (Yes in Step S6), the control device 12terminates the power reduction control (Step S7) and returns to Step S1.Even when the reengagement performed after the occurrence of the geardisengagement is incomplete, and the gear disengagement occurs again,the repetition of the start and termination of the power reductioncontrol in a short period of time is prevented by setting the delay timeas above. The delay time does not have to be set, and the powerreduction control may be terminated when the termination condition issatisfied.

Embodiment 2

FIG. 7 is a block diagram showing a control device 112 and the likeaccording to Embodiment 2. The same reference signs are used for thesame components as Embodiment 1, and the repetition of the sameexplanation is avoided. As shown in FIG. 7 , the control device 112includes the condition determiner 31 and a clutch controller 132 (powercontroller). A clutch actuator 150 is electrically connected to anoutput side of the control device 112. The clutch actuator 150 operatesthe main clutch C (see FIG. 2 ).

When the condition determiner 31 determines that the start condition ofthe power reduction control is satisfied, the clutch controller 132controls the clutch actuator 150 such that the power transmitting ratioof the main clutch C decreases. To be specific, as the power reductioncontrol, the clutch controller 132 controls the clutch actuator 150 suchthat the main clutch C changes from a completely engaged state to ahalf-engaged state. With this, the power reduction control of reducingthe power transmitted from the engine E to the gear transmission 11 isrealized. Since the other components are the same as those described inEmbodiment 1, explanations thereof are omitted.

A processor may include, for example, a CPU (central processing unit). Asystem memory may include a RAM. A storage memory may include a harddisk and/or a flash memory. The storage memory stores programs. Oneexample of a processing circuit is a configuration in which the programread by the system memory is executed by the processor.

The functionality of the elements disclosed herein may be implementedusing circuitry or processing circuitry which includes general purposeprocessors, special purpose processors, integrated circuits, ASICs(“Application Specific Integrated Circuits”), conventional circuitryand/or combinations thereof which are configured or programmed toperform the disclosed functionality. Processors are consideredprocessing circuitry or circuitry as they include transistors and othercircuitry therein. The processor may be a programmed processor whichexecutes a program stored in a memory. In the disclosure, the circuitry,units, or means are hardware that carry out or are programmed to performthe recited functionality. The hardware may be any hardware disclosedherein or otherwise known which is programmed or configured to carry outthe recited functionality. When the hardware is a processor which may beconsidered a type of circuitry, the circuitry, means, or units are acombination of hardware and software, the software being used toconfigure the hardware and/or processor.

As above, the embodiments have been described as examples of thetechnology disclosed in the present application. However, the technologyin the present disclosure is not limited to those and is also applicableto embodiments in which modifications, replacements, additions,omissions and the like are suitably made. Moreover, a new embodiment maybe prepared by combining the components described in the aboveembodiments. For example, some of components or methods in an embodimentmay be applied to another embodiment, and some of components in anembodiment may be separated and arbitrarily extracted from the othercomponents in the embodiment. Furthermore, the components shown in theattached drawings and the detailed explanations include not onlycomponents essential to solve the problems but also components forexemplifying the above technology and not essential to solve theproblems.

What is claimed is:
 1. A method of controlling a geartransmission-equipped vehicle, the gear transmission-equipped vehicleincluding a driving source and a gear transmission that switches anengagement state of an engaging member to switch a change gear ratio ofthe driving source, the engaging member being engaged with a gear, themethod comprising: determining whether or not unintentional geardisengagement has occurred after a speed change step is terminated, thegear disengagement being a state where the engaging member is disengagedfrom the gear; and when it is determined that the gear disengagement hasoccurred, reducing power transmitted between the engaging member and thegear.
 2. The method according to claim 1, wherein determining whether ornot unintentional gear disengagement has occurred includes determiningthat a current gear position of the gear transmission falls within atransition region between engagement regions corresponding to respectivegear positions.
 3. The method according to claim 1, wherein reducing thepower includes reducing an output of the driving source.
 4. The methodaccording to claim 1, wherein the gear transmission-equipped vehiclecomprises a clutch interposed between the driving source and the geartransmission, and a clutch actuator that operates the clutch; andreducing the power includes controlling the clutch actuator such that apower transmitting ratio of the clutch decreases.
 5. The methodaccording to claim 1, further comprising: determining whether or not atermination condition is satisfied, the termination condition being acondition that a speed difference obtained by subtracting a rotationalspeed of the output shaft from a rotational speed of the input shaft isa predetermined value or less; and terminating reducing the power whenthe termination condition is satisfied.
 6. The method according to claim1, wherein further comprising: determining whether or not a terminationcondition is satisfied, the termination condition being a condition thata current gear position of the gear transmission falls within any ofengagement regions corresponding to respective gear positions; andterminating reducing the power when the termination condition issatisfied.
 7. A control device of a gear transmission-equipped vehicle,the gear transmission-equipped vehicle including a driving source and agear transmission that changes a rotational speed of power output fromthe driving source, the control device comprising processing circuitryconfigured to: determine whether or not unintentional gear disengagementhas occurred after a speed change step is terminated, the geardisengagement being a state where the engaging member is disengaged fromthe gear; and when it is determined that the gear disengagement hasoccurred, reduce power transmitted between the engaging member and thegear.
 8. The control device according to claim 7, wherein determiningwhether or not unintentional gear disengagement has occurred includesdetermining that a current gear position of the gear transmission fallswithin a transition region between engagement regions corresponding torespective gear positions.
 9. The control device according to claim 7,wherein reducing the power includes reducing an output of the drivingsource.
 10. The control device according to claim 7, wherein the geartransmission-equipped vehicle comprises a clutch interposed between thedriving source and the gear transmission, and a clutch actuator thatoperates the clutch; and reducing the power includes controlling theclutch actuator such that a power transmitting ratio of the clutchdecreases.
 11. The control device according to claim 7, wherein theprocessing circuitry further configured to: determine whether or not atermination condition is satisfied, the termination condition being acondition that a speed difference obtained by subtracting a rotationalspeed of the output shaft from a rotational speed of the input shaft isa predetermined value or less; and terminate reducing the power when thetermination condition is satisfied.
 12. The control device according toclaim 7, wherein the processing circuitry further configured to:determine whether or not a termination condition is satisfied, thetermination condition being a condition that a current gear position ofthe gear transmission falls within any of engagement regionscorresponding to respective gear positions; and terminate reducing thepower when the termination condition is satisfied.